WebSocket背景

Websocket是html5提出的一個協議規范，參考rfc6455。

websocket約定了一個通信的規范，通過一個握手的機制，客戶端（瀏覽器）和服務器（webserver）
之間能建立一個類似tcp的連接，從而方便c－s之間的通信。在websocket出現之前，web交互一般是
基于http協議的短連接或者長連接。

WebSocket是為解決客戶端與服務端實時通信而產生的技術。websocket協議本質上是一個基于tcp
的協議，是先通過HTTP/HTTPS協議發起一條特殊的http請求進行握手后創建一個用于交換數據的TCP
連接，此后服務端與客戶端通過此TCP連接進行實時通信。

WebSocket協議

框架圖

            jetty
nginx -->   jetty
            jetty

支持 ws 和 wss 協議

軟件版本

Nginx配置

map $http_upgrade $connection_upgrade {
    default upgrade;
    '' close;
}

upstream backend {
    sticky;
    server localhost:6565;
    server localhost:6666;
}

server {
    listen       0.0.0.0:80;
    server_name  foo.bar.com;
    server_tokens off;
    
    location /services/ {
        proxy_pass  http://backend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
        include proxy.conf;
    }

    error_page 497  https://$host$uri?$args;
}

server {
    listen       0.0.0.0:443 ssl http2;
    server_name  foo.bar.com;
    server_tokens off;

    ssl                  on;
    ssl_certificate      ssl/foo.bar.com.crt;
    ssl_certificate_key  ssl/foo.bar.com.key;

    ssl_session_timeout  5m;

    ssl_protocols  SSLv2 SSLv3 TLSv1 TLSv1.1 TLSv1.2;
    ssl_ciphers "ECDHE-RSA-AES256-GCM-SHA384:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA256:ECDHE-RSA-AES256-SHA:ECDHE-RSA-AES128-SHA:ECDHE-RSA-DES-CBC3-SHA:AES256-GCM-SHA384:AES128-GCM-SHA256:AES256-SHA256:AES128-SHA256:AES256-SHA:AES128-SHA:DES-CBC3-SHA:!aNULL:!eNULL:!EXPORT:!DES:!MD5:!PSK:!RC4";
    ssl_prefer_server_ciphers   on;
    ssl_verify_client   off;
    
    location /services/ {
        proxy_pass  http://backend;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection $connection_upgrade;
        include proxy.conf;
    }

    error_page 497  https://$host$uri?$args;
}

重點就三行

proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection $connection_upgrade;

Jetty配置

1. 拷貝 JETTY_HOME/modules/websocket.mod 至 JETTY_BASE/modules/websocket.mod
2. 創建 JETTY_HOME/start.d/websocket.ini 內容如下

--module=websocket

SpringMvc配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:websocket="http://www.springframework.org/schema/websocket"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
            http://www.springframework.org/schema/beans/spring-beans.xsd
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc.xsd
            http://www.springframework.org/schema/context
            http://www.springframework.org/schema/context/spring-context.xsd
            http://www.springframework.org/schema/websocket
            http://www.springframework.org/schema/websocket/spring-websocket.xsd">
    <!-- websocket -->
    <websocket:handlers>
        <websocket:mapping path="/echo" handler="echoWebsocketHandler"/>
        <websocket:handshake-handler ref="handshakeHandler"/>
    </websocket:handlers>
    <bean id="handshakeHandler" class="org.springframework.web.socket.server.support.DefaultHandshakeHandler">
        <constructor-arg ref="upgradeStrategy"/>
    </bean>
    <bean id="upgradeStrategy" class="org.springframework.web.socket.server.jetty.JettyRequestUpgradeStrategy">
        <constructor-arg ref="serverFactory"/>
    </bean>
    <bean id="serverFactory" class="org.eclipse.jetty.websocket.server.WebSocketServerFactory">
        <constructor-arg ref="servletContext" type="javax.servlet.ServletContext"/>
        <constructor-arg ref="webSocketPolicy" type="org.eclipse.jetty.websocket.api.WebSocketPolicy"/>
    </bean>
    <bean id="webSocketPolicy" class="org.eclipse.jetty.websocket.api.WebSocketPolicy">
        <constructor-arg value="SERVER"/>
        <property name="inputBufferSize" value="8092"/>
        <property name="idleTimeout" value="600000"/>
    </bean>
</beans>

參考

1. Websocket協議的學習、調研和實現
2. Nginx WebSocket Proxying